Apparatus and method for the manufacture of chipboards



E. GRETEN April 3, 1962 APPARATUS AND METHOD FOR THE MANUFACTURE OF CHIPBOARDS '3 Sheets-Sheet 1 Filed Nov. 7, 1957 E. GRETEN April 3, 1962 APPARATUS AND METHOD FOR THE MANUFACTURE OF CHIPBOARDS '3 Sheets-Sheet 2 Filed Nov. 7, 1957 FIG. 4

E. GRETEN April 3, 1962 APPARATUS AND METHOD FOR THE MANUFACTURE OF CHIPBOARDS '3 Sheets-Sheet 5 Filed Nov. 7, 1957 FIG. 6

M/VE/VTOR United States Patent 3,028,287 APPARATUS AND METHOD FOR THE MANU- FACTURE 0F CHIPBOARDS Ernst Greten, Springe, near Hannover, Germany, assignor to Bahre Metallwerk Kommanditgesellschaft, Springe, near Hannover, Germany, a German company Filed Nov. 7, 1957, Ser. No. 694,975 Claims priority, application Germany Nov. 9, 1956 Claims. (Cl. 156-455) This invention relates to an apparatus for forming a fleece of wood chips, which may have a binding'agent applied thereto, for the production of chipboards.

An object of the invention is to provide a fleece of the aforesaid type which contains relatively fine chips at its surfaces and relatively coarse chips in its central layers. The coarse chips give good insulating properties to the chipboards made from the fleece, since the coarse chips form cavities between each other. The relatively fine chips situated at the surfaces of the fleece give the finished chipboard a good appearance, so that in many cases it is not necessary to cover the chipboard with a special wood veneer.

According to the present invention such apparatus comprises a mat forming elongated chamber, said chamber being open at the bottom, an air blower positioned substantially centrally in said chamber, means for directing air currents from said blower through the upper portion of said chamber and towards each end of said chamber means for directing a supply of wood chips to each side of said blower, and conveyor means moving continuously under the lower end of said chamber.

In a preferred form the apparatus comprises a chamber, said chamber being rectangular in plan with its length appreciably greater than its width, a continuously moving conveyor, said conveyor substantially closing the lower end of said chamber, a housing or plenum chamber positioned centrally in said mat forming chamber and separating at least the upper portion of said chamber into two parts, an air blower mounted in said housing, said housing having an air outlet comprising apertures in one side through which air can pass into the upper portion of one of said two parts of the chamber and having a second air outlet also comprising apertures in the opposite side through which air can pass into the upper portion of the other of said two parts of the mat forming chamber, and means for directing a supply of wood chips into the air coming from each of said outlets, said chamber having two end walls and each end wall having at least one aperture in the upper part thereof through which air can leave the mat forming chamber. The suction duct of the air blower may be connected to the outer ends of the chamber by return air conduits, the latter containing throttle means, the places where the air conduits are connected to the chamber being situated at such a height above the conveyor that the air currents travelling towards the inlets of the conduits no longer have any substantial influence on the wood chips situated in the vicinity of the conveyor in the chamber.

Thus, each of the two air currents may be independently adjustable and guided at such a height above the conveyor that the wood chips have time, after leaving the air current, to adjust themselves into the natural position of suspension, i.e. with their main axis horizontal.

Chipboards which are made from a fleece formed in this manner have the advantage of great bending strength. The use of the return air conduits has the advantage that the apparatus can also utilize very fine, powder-like wood chips. The quite fine chips, which do not leave the air current, first of all travel along the cyclic path of flow with the air currents. But they are not discharged into the atmosphere and therefore cannot leave the working zone. In time, these fine chips become consolidated by accumulating together and by accumulating on relatively coarse chips. In this way they are also worked into Chipboards. Thus, it is an important feature of the invention that, for the purpose of distributing the wood chips, there are used two independently adjustable air currents which are guided along a cyclic course by means of a blower through distributing chambers and are spaced at such distances from the conveyor belt that they no longer have any influence on the wood chips when the latter comeinto the vicinity of the conveyor belt.

The invention further relates to apparatus for the continuous production of Wood chips provided with a binding agent. To this end the apparatus may comprise a further chamber which is provided at the top with an aperture through which wood chips can be introduced. Air from the blower is directed through an opening at one side of the chamber, and at difierent distances from this opening a plurality of apertures are provided to which are connected means for applying binding agents to the groups of wood chips delivered to the opening by the air flow. Adjoining the means for applying binding agents is a continuous conveyor, which accommodates all the groups of wood chips which have meanwhile been provided with binding agent.

The device for applying binding agent may be composed of a plurality of parallel-arranged drums in which the chips are rolled about and sprayed with glue. Alternatively the device for applying binding agent may consist of a single drum provided with nozzles, through which drum the chips travel continuously, in the axial direction and to which drum the various chips are fed through the apertures which connect with the drum at different points, in such manner that the chips take different lengths of time to pass through the drum according to their relative size. p 1

One construction of apparatus for forming a mat of wood chips, associated with means for first applying a binding agent thereto, will now be described by way of example only, reference being made to the accompanying drawings, in which:

FIGURE 1 is a part-sectional side elevation of the apparatus for the continuous formation of a mat of wood chips to which a binding agent .has been applied.

FIGURE 2 is a plan view of the apparatus shown in FIGURE 1,

FIGURE 3 is a part-sectional side elevation of one form or": the gluing device,

FIGURE 4 is a plan view of the device shown in FIG- URE 3,

FIGURE 5 is a part-sectional side elevation of a modifled construction of gluing device, which in this case only has a single drum, and

FIGURE 6 is a sectional view taken on the line VIVI of FIGURE 5.

A conveyor belt or conveying plates 5 is moved continuously through two chip-distributing mat forming chambers 3, 4. The joints between each two conveying plates 5 can be covered by loosely applied narrow plates 6. Situated between the distributing chambers 3, 4 in a chamber 7 is an air blower 8 which causes currents of air to pass in substantially a horizontal direction through the apertures 9 into the chambers 3, 4, which may be regarded as a single chamber, with the plenum chamber acting as a partition or wall therein.

Situated above the air inlet apertures 9 are material inlet means such as hoppers 10 through which thechipboard material is fed, the said material consisting of'non-graded, but glued, chips, some relatively coarse and, the remainder relatively fine. The air currents passing intothe 3 distributing chambers 3, 4 through the apertures 9 divide up the material fed in at 10 in such a manner that therelatively coarse chips fall downwards near the plenum chamber 7 whilst the relatively fine chips are carried away by the air current. The finest chips are carried over the greatest distance.

Connected to the ends of the distributing chambers 3 and 4 at apertures remote from the air inlet apertures 9, are air return conduits 11, 12 which lead back to the suction duct of the blower 8. Arranged in the conduits 11, 12 are throttle elements 13. This arrangement makes it possible to adapt the chip-distributing distance to actual conditions, i.e. to take into'account the composition of the chips, their moisture content and the like.

It will be readily appreciated that on the conveying plates 5 which are moved continuously through the distributing chambers 3, 4 there is formed a mat of chips which contains the finest chips at its lower side and upper side, whilst it contains the relatively coarse chips in its central layers. Since both the air inlet apertures 9 and the air outlet apertures 15 are arranged at appreciable heights above the conveying plates 5, the result is achieved that the air currents passing from 9 to 15 no longer have any quantity regulating device 16, a fan 17, a sorting bin 18,

three rotating drums 19, 20, 21 and a conveyor belt 22.

The quantity regulating device 16 feeds the non-graded coarse and fine chips to the feed hopper 23 through which the flow of chips passes vertically downwards into the sorting bin 18. Upon entering the bin 18, the chips are subjected to an air. current which is produced by the fan 17. A grating 24 is used for distributing the air uniformly.

As in the case of an air separator, the relatively fine wood chips are conveyed further by the air current than are the relatively coarse chips. The bin 18 has three outlets 25, 26, 27. The thickest chips reach the outlet 25, since these chips are conveyed laterally to the least extent. Medium chips come to be situated in the outlet 26, whilst the relatively fine chips mainly reach the outlet 27.

Situated below each of the three outlets is a drum, in which the chips are circulated and are sprayed with glue through nozzles 28. If the period during which the chips remain in the individual drums 19, 20, 21 are of equal duration, the nozzles in the drum 1% will be the longest and the greatest in number, those in the drum 20 will be somewhat smaller and fewer in number, whilst the nozzles in the drum. 21 will be smallest and least in number. The result is that the chips of various sizes are glued approximately uniformly, on the basis of the ratio of the quantity of glue to the weight of an individual chip. From the drums 19, 20, 21 the glued chips reach the conveyor belt 22 from which they are eventually taken to the hoppers 10 (FIGURES 1 and 2).

In the embodiment according to FIGURES 5 and 6, the parts 16, 17, 18 are constructed in the same way as the corresponding parts in FIGURES 3 and 4. Their method of operation is also the same. Instead of the three drums according to FIGURES 3 and 4, the apparatus according to FIGURES 5 and 6 comprises only a single drum 29. This is so arranged that it is situated below all three outlets 25, 26, 27 of the bin 18. The outlet 25 is situated near the beginning of the drum, the outlet 27 substantially above the centre of the drum. As a result, the chips in passing axially through the drum 29 are subjected for various lengths of time to the action of the glue spraying jets, namely the coarse chips fed in at 25 are subjected for the longest period of time or considered in another way, to the action of all the jets and the line chips fed in at 27 are subjected to the glue jets for the shortest period of time or considered in the other way, to the action of only some of the jets.

The degree to which the various chips are glued can be controlled by appropriate selection and adjustment of the gluing nozzles 28.

What I claim is:

1. In apparatus for forming a mat of wood chips for the production of chipboards, two chip-distributing chambers, said chambers being rectangular in plan with their length appreciably greater than their width, a continuously moving conveyor, said conveyor substantially closing the lower end or" said chambers, a third chamber, said third chamber being situated between said two chip-distributing chambers, an air blower mounted in said third chamber, said third chamber having an air outlet in one side through which air can pass into the upper portion of one of said two chip-distributing chambers, said third chamber having a second air outlet in the opposite side through which air can pass into the upper portion of the other of said two chip distributing chambers and means for directing a supply of wood chips into the air coming from each of said air outlets, each of said two chip-distributing chambers having an end wall and each end wall having at least one aperture in the upper part thereof through which air can leave the respective chip-distributing chamber.

2. In apparatus for forming a mat of wood chips for the production of chipboards, two chip-distributing chambers, said chambers being rectangular in plan with their length appreciably greater than their width, a continuously moving conveyor, said conveyor substantially closing the lower end of said chambers, a third chamber, said third chamber being situated between said two chip-distributing chambers, an air blower mounted in said third chamber, said third chamber having an air outlet in one side through which air can pass into the upper portion of one of said two chip-distributing chambers, said third chamber having a second air outlet in the opposite side through which air can pass into the upper portion of the other of said two chip distributing chambers, means for directing a supply of wood chips into the air coming from each of said air outlets, each of said two chip-distributing chambers having an end wall and each end wall having at least one aperture in the upper part thereof, a plurality of air conduits each extending from a respective one of the end wall apertures to said third chamber, and a plurality of air flow control means, each of said air conduits having an air flow control means positioned in the conduit for control of the air flow therethrough.

3. An apparatus for forming a mat composed of particles of material for the production of boards, panels or sheets, a mat forming chamber, said chamber having an open bottom portion, a conveyor mounted beneath said bottom portion for closing the said bottom portion of said mat forming chamber, a plenum chamber positioned substantially centrally in said mat forming chamber, said mat forming chamber having inlet means for said material mounted adjacent said plenum chamber, said plenum chamber having a pair of spaced walls, aperture means in each of said spaced walls located beneath and closely ad jacent said inlet means, said plenum chamber being spaced above said conveyor, said mat forming chamber having an 'air outlet at opposite ends of said chamber adjacent the upper surface thereof, and return conduit means for said air outlets, said return conduit means being connected into said plenum chamber, said plenum chamber and said conduit means forming passageway means for air recirculation, and an air blower in said passageway means whereby the air in each end of said mat forming chamber is recirculated by said blower.

4. An apparatus for forming a mat composed of particles of material for the production of boards, panels or sheets, a mat forming chamber, said chamber having an open bottom portion, a conveyor mounted beneath said bottom portion for closing the said bottom portion of said mat forming chamber, a plenum chamber positioned substantially centrally in said mat forming chamber, said mat forming chamber having inlet means for said material mounted adjacent said plenum chamber, said plenum chamber having a pair of spaced walls, aperture means in each of said spaced walls located beneath and closely adjacent said inlet means, said plenum chamber being spaced above said conveyor, said mat forming chamber having an air outlet at opposite ends of said chamber adjacent the upper surface thereof, and return conduit means for said air outlets, said return conduit means being connected into said plenum chamber, and an air blower for said plenum chamber whereby the air in each end of said mat forming chamber is recirculated by said blower.

5. The structure of claim 3 wherein said passageway means is provided with means for controlling the amount of air passing therethrough.

6. The structure of claim 4 wherein said return conduit means is provided with means for regulating the amount of air passing theretbrough.

7. An apparatus for forming a mat of wood chips for the production of chipboards, a chamber, said chamber having an open bottom portion, a conveyor mounted beneath said bottom portion for closing the said bottom portion of said chamber, a housing positioned centrally of said chamber, said chamber having a hopper mounted adjacent said housing, said housing having a air of spaced walls, a plurality of apertures in each of said spaced walls located beneath and to one side of its hopper, said housing having a bottom portion spaced above said conveyor, an air blower mounted to expel air from said housing, said chamber having an air outlet at opposite ends of said chamber, said air outlet being located on each side of said housing adjacent the upper surface thereof, and return conduits for said air inlets, said return conduits being connected into said housing whereby the air in each end of said chamber is recirculated by said blower.

8. The structure of claim 7 wherein means is provided in said return conduits for controlling the amount of air passing therethrough.

9. A method of forming an air laid mat which comprises a downward introduction of a curtain of varied size particles into a first deposition chamber, deflecting said particles by introducing a steady horizontally moving stream of air through said curtain at substantially right angles thereto, moving a conveyor under said chamber in a direction generally parallel to said stream of air for deposition of said particles into a mat thereon and for removal of said mat from the chamber, a downward introduction of a second curtain of varied size particles into a second deposition chamber, deflecting said particles by introducing a steady stream of air moving in a generally horizontal direction but opposed to that of the first mentioned stream, depositing particles from said second curtain on said conveyor above the particles deposited from said first deposition chamber and controlling each of said horizon-tally moving streams of air by recirculating air from each deposition chamber for reintroduction to said deposition chambers.

References Cited in the file of this patent UNITED STATES PATENTS 465,582 Mundy Dec. 22, 1891 1,854,100 Brito Apr. 12, 1932 1,951,684 Wells Mar. 20, 1934 1,998,875 Koda Apr. 23, 1935 2,255,206 Duncan Sept. 9, 1941 2,420,368 Giordano May 13, 1947 2,489,079 Clark et a1 Nov. 22, 1949 2,544,019 Heritage Mar. 6, 1951 2,624,079 Duvall Jan. 6, 1953 2,658,847 MacDonald Nov. 10, 1953 2,688,393 Uschmann Sept. 7, 1954 2,743,758 Uschmann May 1, 1956 2,771,387 Kleist et al. Nov. 20, 1956 2,777,170 Mandarin Jan. 15, 1957 2,940,134 Heritage June 14, 1960 

1. IN APPARATUS FOR FORMING A MAT OF WOOD CHIPS FOR THE PRODUCTION OF CHIPBOARDS, TWO CHIP-DISTRIBUTING CHAMBERS, SAID CHAMBERS BEING RECTANGULAR IN PLAN WITH THEIR LENGTH APPRECIABLY GREATER THAN THEIR WIDTH, A CONTINUOUSLY MOVING CONVEYOR, SAID CONVEYOR SUBSTANTIALLY CLOSING THE LOWER END OF SAID CHAMBERS, A THIRD CHAMBER, SAID THIRD CHAMBER BEING SITUATED BETWEEN SAID TWO CHIP-DISTRIBUTING CHAMBERS, AN AIR BLOWER MOUNTED IN SAID THIRD CHAMBER, SAID THIRD CHAMBER HAVING AN AIR OUTLET IN ONE SIDE THROUGH WHICH AIR CAN PASS INTO THE UPPER PORTION OF ONE OF SAID TWO CHIP-DISTRIBUTING CHAMBERS, SAID THIRD CHAMBER HAVING A SECOND AIR OUTLET IN THE OPPOSITE SIDE THROUGH WHICH AIR CAN PASS INTO THE UPPER PORTION OF THE OTHER OF SAID TWO CHIP DISTRIBUTING CHAMBERS AND MEANS FOR DIRECTING A SUPPLY OF WOOD CHIPS INTO THE AIR COMING FROM EACH OF SAID AIR OUTLETS, EACH OF SAID TWO CHIP-DISTRIBUTING CHAMBERS HAVING AN END WALL AND EACH END WALL HAVING AT LEAST ONE APERTURE IN THE UPPER PART THEREOF THROUGH WHICH AIR CAN LEAVE THE RESPECTIVE CHIP-DISTRIBUTING CHAMBER. 